Very often, the performance of timepiece movements, or the possibility of housing particular complications or functions are limited by the need to guide the pivoting wheel sets by pivots secured to plates or bridges. This guiding is generally achieved, at least for wheel sets with high angular velocity, via the cooperation, on each side of the wheel set, between an arbour comprised in the wheel set and a jewel comprised in the plate or bridge.
Cantilever arrangements, which would free space at least on one side of the wheel set, to house other components of the movement, are rare, because of the care required for the manufacture thereof, and the high associated manufacturing cost. An example of this is provided by CH Patent No. 682 871 in the name of FREDERIC PIGUET, for manufacturing an ultra-flat movement, wherein all the wheel sets are mounted in a cantilever arrangement on a single plate, each via a ball bearing mounted, on the one hand on the plate and on the other hand on an arbour comprised in the wheel set. In the same Patent, a drum-shaped ratchet surrounds the barrel and is pivoted on the periphery thereof by three rollers each pivoted on a ball bearing, and the barrel is pivoted in the ratchet by means of a ball bearing. This type of assembly greatly improves accessibility to the interior of the movement compared to conventional movements, but the wheel sets are still fitted with arbours of small diameter and great precision is required to fit said arbours in the bearings and axial holding means have to be provided. The axial holding may be achieved by shrinking the arbour on the inner cage of the bearing, which means it cannot be used for wheel sets made of fragile materials such as silicon or similar.
For wheel sets of large dimensions and slow angular velocity, such as tourbillons, karussels or barrels, it is also known to hold on a shoulder of relatively large diameter with a very thick ball bearing, as in CH Patent No. 687 795 in the name of OMEGA, which discloses a tourbillon in a cantilever arrangement supported on its base only by a bearing of this type. A flying karussel like that of EP Patent No. 1 995 650 in the name of BLANCPAIN includes a carriage carried by a wheel set of large dimensions, carried by a ball bearing fixed to a bridge.
The FR patent No. 2 886 995 in the name of SEIKO still discloses a ball bearing device for automatic winding.
However, these applications only concern wheel sets with high inertia, and no alternative to conventional guiding using an arbour and pivot is known for wheel sets with lower inertia, and/or higher angular velocity.
Moreover, it is generally necessary to equip the pivots of the most sensitive members, such as those of the regulating mechanism, with anti-shock devices, which involve considerable expense and require considerable space.
For these regulating mechanisms, it is again a question of reducing the influence of the play of the pivots according to the position of the timepiece in space, which generally leads to different operating parameters according to said position and, in particular to variations in the oscillation amplitude of the balances.